JPH03128774A - Chassis frame for truck - Google Patents

Abstract

PURPOSE:To improve the durable strength of the coupling part between a cross member and a side rail by a method wherein a device is made on arrangement of a plurality of rivets or bolts by means of which upper and lower longitudinal flanges are fastened against the web of a side rail. CONSTITUTION:A plurality of rivets or bolts 20u and 20l by means of which upper and lower longitudinal flanges 18uf and 18l are respectively fastened against a web 12w of a side rail 12 are prevented from being disposed in at least the one of regions OMEGAi (i=1-4; i=1 or 2 are upper longitudinal flanges, and i=3 and 4 are lower longitudinal flanges) satisfying a formula of each longitudinal flange. But, in a local coordinate system having two ends 0i, being apexes, of the bent lines of the upper and lower longitudinal flanges, epsiloni is a coordinate in a direction extending along a bent line, in a local coordinate system having coordinates <=i:Oi, being an original point, epsiloni is a coordinate in a direction extending at right angles with a bent line, ai is the length of each of the bent lines of the upper and lower longitudinal flanges, and (b) is a distance between the bent lines of the upper and lower longitudinal flanges.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a truck chassis frame.

(Prior Art) An example of the configuration of a conventional truck chassis frame will be explained with reference to FIGS. 1 and 2, which show an embodiment of the present invention, and FIG. 12 for convenience. .

The reference numeral 10 in the figure generally indicates a chassis frame, and the chassis frame 10 includes a pair of left and right side rails 12 extending in the longitudinal direction of the vehicle and each having a channel-shaped cross section.
and a so-called allicator type cross member 14 having a pair of left and right end portions fixed to the side rail 12 extending in the width direction of the vehicle. The cross member 14 is
An upper member 14u having a hat-shaped cross-sectional shape, and a flat plate having an arbitrary cross-sectional shape such as a cross-sectional groove or pole 16 fastened to at least both ends of the upper member An upper flange 18u and a lower flange 18t, which are expanded in a V-shape, are formed at both end portions of the upper member 14u and the lower member 14t in the vehicle width direction. The upper flange 18u and the lower flange 18t are each extended outward in the vehicle width direction and bent in the vertical direction to form an upper flange 18uf and a lower vertical flange 18tf, respectively.

The upper and lower vertical flanges 18uf and 18tf are connected to a plurality of fastened cross-sectional grooves or belts 20u and 2, respectively.
0t to the web 12W of the side rail 12.

1 and 2, an alligator-shaped cross member 1 is shown.
4 is exemplified, but as is well known in the art, a cross member having a groove-shaped cross-section, a cross member having an I-shaped cross-section, etc. are appropriately employed.

Above upper flange I 8 uf and lower vertical flange 1
A typical arrangement of fastened cross-section grooves or bolts 20u and 201 for fastening the webs 2wK of the side rails 12, respectively, is illustrated in FIG. This figure is a front view of the vertical flanges 18uf and 18tf, and
X is the horizontal center line, Y-Y is the vertical center line, 01-
0 is the joining line or bending line between the lower part 72 angle 18uf and the upper flange 18u, 03-04 is the lower vertical flange 18
fij' and the lower flange 184, that is, the bending line h''b is the upper and lower vertical flanges 18uf and 1
The lengths of the above-mentioned bends SO, -O2 and 03-04 of 8 tf, b is the distance in the vertical direction between the bend lines 01-02 and o3-o4.

While the truck is running, vertical bending, torsion, and lateral bending loads, as well as their combined loads, act on the undercarriage frame 10, so the side rails 12 and cross members 4
In order to increase the bonding strength with the upper vertical flange 18uf
and the lower longitudinal flanges 18 tf to the web 12W of the side rail, respectively (20u and 20t) are symmetrically connected with respect to the longitudinal centerline Y-Y, as is almost customary in the past , and each vertical 7 lands I
A plurality of (six in the illustrated case) are arranged substantially in a line parallel to the lateral center line XX of 8 uf and 18 tf.

(Problem to be Solved by the Invention) The upper flange 18uf and the lower vertical flange 18tf formed at both end portions in the vehicle width direction of the cross member 4 are arranged in a turn as shown in FIG. A torsional test was carried out on the above chassis frame, which was fastened to the side rails 112wK by the fastened cross-sectional groove type or pole) 20u and 20t, focusing on the most important torsional load among the various loads mentioned above that act during driving. As a result,
The fastened cross-sectional grooves or poles h20u and 201 included in the four triangular areas Ωi to Ω4 (these areas Ω1 to Ω4 will be explained in detail later) indicated by diagonal lines in the figure, and their Peripheral plate members (side rail unibu 12w.

Plate material forming vertical flanges 18 uf and 18 tf)
If an extremely large stress is generated in the area and the belt is repeatedly driven on rough roads, the fastened cross-sectional groove or belt in the above area may break, or the plate member around the fastened cross-sectional groove or bolt may crack. It has been found that such defects are likely to occur.

The present invention provides a web of a side rail having a groove-shaped cross-section, and a plurality of upper and lower flanges each formed by vertically bending the extension portions of both ends of the upper and lower flanges of a cross member. By attaching a button to the undercarriage frame fastened by grooves or belts, and adding a twist to the arrangement of the fastened cross-sectional grooves or belts that fasten the upper vertical flange and the lower vertical flange to the web of the side rail, twisting and The purpose is to reduce the stress generated in the fastened cross-sectional groove type or bolt and the surrounding plate members while ensuring bending rigidity, and to improve the durability of the cross member connecting portion to the side rail.

(Means for Solving the Problems) The truck chassis frame according to the present invention consists of the following two inventions devised to achieve the above object. A pair of left and right site 9 rails each having a groove-shaped cross-sectional shape and a pair of left and right upper and lower flanges extending in the width direction of the vehicle were bent in the vertical direction to form vertical flanges. The above-mentioned upper and lower flanges and lower bolted flanges are each fastened to the web of the side rail by attaching the flanges to a cross member having an allied type cross member fastened to the web of the side rail by a plurality of glued pets or bolts. The region Ω1 (i=1 to 4; i=1 and the lower longitudinal flange, i
= 3 and 4 are lower scores of 7 U/J).

That is, ξ1: Coordinates in the direction along the bending line with the button on the local coordinate system with the origin at both ends O1 of the bending line of the upper and lower vertical flanges. Coordinate in the direction perpendicular to the bending line a: Length b of the bending line of the upper and lower flanges 2) Distance between the bending lines of the upper and lower flanges At least one of the areas defined by the following formula: It is characterized by that it is not arranged in one area. Further, the second invention is to fold in the vertical direction a pair of left and right side rails extending in the front-rear direction of the vehicle body, each having a groove-shaped cross section, and an extended portion of both ends of a pair of left and right upper and lower flanges extending in the vehicle width direction. Each of the vertical flanges is bent to form a vertical flange, and each vertical flange is provided with a plurality of cross members having a grooved cross section or an I-shaped cross section fastened to the web of the side rail with bolts. In the above, a plurality of fastened cross-sectional grooves or bolts that fasten the upper vertical flange and the lower threaded flange to the web of the side rail, respectively, have an area ΩH (i=1 to 4; i
= l and lower vertical 7 runs, i == 3 and 4 are lower flange), i.e., ξ1: Both ends of the bending line of upper and lower flange Coordinate in the direction along the bending line ηi = Coordinate in the direction perpendicular to the bending line in the local coordinate system with the above Oi as the origin A1: Length b of the bending line of the upper and lower vertical flanges 2 Upper and lower The truck chassis frame is characterized in that the frame is not disposed in at least one region defined by the equation of the distance between the bending lines of the bending flange.

(Function) According to the present invention, by arranging a plurality of fastened cross-sectional grooves or bolts in the flange surface excluding the above region Ω1 in the upper and lower vertical flanges of the cross member, both ends of the cross member relative to the side rail While ensuring the torsional rigidity of the joint, the stress generated in the fastened cross-sectional groove type or bolt and its surrounding plate members is reduced.

This makes it possible to improve the durability and strength of the joint.

(Example) Examples of the present invention will be specifically described below with reference to the accompanying drawings. (It should be noted that matters already explained in connection with the above-mentioned conventional configuration will not be repeated.) First, the first embodiment of the present invention shown in FIGS. 1 to 3 will be described. 4 turns of the arrangement of the fastened cross-sectional groove type or R-ruts 20u and 201 that fasten the upper and lower vertical flanges 18uf and 18tf formed at both ends of the member 14 in the grassland direction to the web 12W of the side rail 12, respectively. is the third
clearly shown in the diagram. Upper flange 18 as shown
The six fastened cross-sectional grooves (poles) 20u arranged on the vertical flange 18uf of There is. Similarly, lower flange 1st
The six fastened cross-sectional grooves or bolts 20t arranged on the vertical flange 18tf are all arranged within the 7-rank plane except for the elongated triangular region Ω3 or Ω4 shown with diagonal lines.

The above region Ω1 includes the upper flange 18u and the vertical flange 18
One end of the joining line with uf, that is, the bending line 0-0 of the vertical flange, for example, the front end 01, is the origin, and the coordinate system is 2. Similarly, the area Ω2 is the elongated triangular area represented by the bending line 01-02 in a local orthogonal coordinate system with the origin at the other end of the bending line 01-02, for example, the rear end 02. Let ξ2 be the coordinate in the direction along.

It is a rectangular area. As shown in the figure, referring to the lower flange, in the previous configuration shown in FIG. 12, areas 01 to Ω4, which are exactly the same as those in FIG. 3, were set on the upper vertical flange 18uf and the lower vertical flange 1Stf. In this case, among the three fastened cross-sectional grooves (pol) 20u and 201 located on the left side of the center line Y-Y, the two fastened cross-sectional grooves on the side far from the concentric line The mold or bolt has at least a portion of its respective cross-sectional area contained within these regions.

Now, in the upper part of FIG. 4, a perspective view of the end part of the cross member 14 fastened to the web of the side rail is drawn,
On the upper and lower longitudinal flanges 13uf and 1111f, there are rows A near and parallel to the bend lines O4-02 and o5-o4, respectively, and the bend lines O-0 and 05-
04 and parallel to them, and the first row closest to the concentric line in the direction parallel to the vertical center line Y-Y (vertical direction).

A fastened cross-sectional groove or bolt placement pattern is illustrated, consisting of a middle second row and a farthest third row. It was. In the middle of the figure, a cross-sectional groove type or bolt 20 that has been fastened is shown.
Stress sensitivity to torsional moment of the vertical flange joint ("IF
'Ax2% t・m) and torsional rigidity (#fm2)
(Df'-ta is shown, and in this data the symbol ○(
The symbol Δ (white triangle) indicates the torsional rigidity.

Finally, in the lower part of the same figure, four types of arrangement patterns Pa#1 of the fastened cross-sectional groove type or M bolts 20u and 20t are shown.
- A schematic diagram showing the type of Pa#4 and the concrete fastened cross-sectional groove type or port position is described.

The arrangement groove turn of the conventional fastened cross-sectional groove type or bolts 20u and 20t shown in FIG. 12 corresponds to the groove turn Pa#1 in FIG. 4, and the bending line 0. -02 and o,
- 1st in column A near o4. All of the second and third rows, namely A, , A2 . A cross-sectional groove type or bolt fastened to A is arranged. tfc, Nozzle yPa #2 in Fig. 4 corresponds to the first embodiment of the present invention shown in Figs. , the cross-sectional groove type or bolt fastened only in the first row (therefore A1) of the center line Y-Y is placed, and the concentric line Y-
The second and third rows far from Y are folded IvlilOl.
-02 and B row far from 03-04, that is, B2. A cross-section groove type or belt fastened to B3 is arranged, respectively.

Comparing patterns Pa#l and Pa#2, there is not much difference between them in terms of torsional rigidity of the upper and lower vertical flanges, but nose turn Pa#l has higher stress sensitivity than P.
It is shown that it is much larger than a#2. Therefore, if the conventional upper and lower vertical flange joints are repeatedly driven on rough roads, the most difference from the center line Y-Y is A3.
The maximum stress is generated in the bent or belt, which may cause the fastened cross-sectional groove or belt to rupture, or cause the side rail uni 12wr or (and) above and around the fastened cross-sectional groove or belt to Lower vertical flange 18uf, 18
Although cracks are likely to occur in the tf, the structure of Nosoturn Pa#2 according to the present invention has extremely low stress sensitivity.

The durability of the upper and lower vertical flange joints has been significantly improved, and the risk of damage to the connected cross-sectional groove or belt and the surrounding side rail unibu and/or cross member vertical flange is extremely small, making it highly reliable. There are high advantages.

Next, the groove turn Pa#3 in FIG.
20u.

20t in the regions Ω1 and Ω2. The bonding lines 01-02°o, respectively, so as not to belong to either Ω3 or Ω4.
- Each fold in row B far from o4 B, , B2. B
This shows a modified example of the arrangement in 3. It is clear from the test results that this modification can also reduce the stress sensitivity while ensuring sufficient torsional rigidity of the loss member joint, substantially in the same way as the above-described turn Pa#2. Furthermore,
Turn Pa#4 in Fig. 4 connects four fastened cross-sectional grooves or belts that fasten the upper and lower vertical flanges to the side rail nib in the first row of column A and the first row of column B, respectively. The second line of A4. B2 shows another variant, where all these fastened cross-sectional grooves or belts are in the area Ω
It is not included in any of 1 to Ω4. In this modification as well, while ensuring the torsional rigidity of the upper and lower cross member joints between the above-mentioned noso turns Pa#2 and Pa#3 and the cross member, the stress sensitivity thereof is significantly reduced compared to the conventional configuration, that is, Pa#1. This has the advantage of effectively improving the durability and reliability of the joint.

Next, FIG. 5 shows upper and lower vertical flanges formed by extending the ends of the upper and lower flanges 18u and 18t of the alligator-shaped loss meter/bar 14 similar to the above and extending them outward in the direction of the grassland and bending them in the vertical direction. 18uf and 18tf are formed so as to point away from each other, and are fastened to the cross-sectional groove type or bolts 20u and 201 of the web 1 of the city trail.
2W shows the second embodiment of the present invention, and the sixth embodiment of the present invention is
This figure is a front view similar to that shown in FIG. 3, showing the arrangement zf turns of the fastened cross-sectional groove type or bolts 20u and 201 according to the same embodiment. Is Figure 6 1 of Figure 4? Turn Pa#2
(Bending line 0.-09, 0z-0
The fastened groove-shaped cross-sections or bolts 20u and 20t (different only in the relative position of □) are all arranged on the flange surface other than the regions Ω1 to Ω4.

In this second embodiment as well, in substantially the same way as in the first embodiment, the connection portion between the upper and lower vertical flanges 18uf and 18tf and the side rail nib 12w is covered, while ensuring sufficient torsional rigidity. It has been found that the stress sensitivity can be significantly reduced compared to conventional configurations, thus improving the durability and reliability of the joint. Then, the fastened cross-sectional groove type or bolts 20u and 20t are bent along the bending line o1-o2. Regarding o3-o4, /zo turn P in Figure 4
Even when they were placed in the same relative positions as a#3 and Pa#4, substantially the same effects as in the first embodiment were obtained.

Furthermore, although not shown, in a case where the vertical flanges 18 uf and 18 tf formed by bending in the vertical direction at the end of the cross member 14 extend in a direction close to each other, contrary to FIG. A bending line 0.0. -02 is arranged and is also arranged downward, while ensuring the torsional rigidity at the joint between the end of the cross member 14 and the side rail unibu i2W, as in each of the above embodiments. It has been confirmed that the stress sensitivity can be significantly reduced compared to conventional configurations. Above 1. Although the description has been made for the case in which it is disposed within the second implementation, it is not limited to this, and the fastened cross-sectional groove type or melt is in the plane excluding at least one area among the above four areas. It may be arranged.

Next, the second invention will be explained. This second invention differs from the first invention in terms of its structure.The first invention has an alligator-type cross member, whereas the second invention
The present invention has a groove-shaped or I-shaped cross section, and the other configurations are the same for both.

Hereinafter, a first embodiment of the second invention will be described with reference to FIGS. 7 and 8. In this embodiment, the crossmere hull 14 is composed of a groove-shaped member consisting of upper and lower flanges 14u and U14t and a nib 14W, and the upper flange 14u
Upper and lower vertical flanges 14uf and 14tf are formed by bending the outer extensions of the lower flange 14t in the vehicle width direction in the vertical direction, respectively, and these vertical flanges 14uf and 14tf each have a plurality of glue propellers) 2
Web 12 of side rail 12 by 0u and 20t
It is concluded □ to w.

Even if this first embodiment is used, the upper vertical flange 14 uf
and the cross-sectional groove type or bolts 20u and 20t that are fastened to the side rail nib 12W,
Similarly to the first embodiment and the modified example, the bending lines o, -o2 . By arranging it on the vertical flange surface other than the area 01 to Ω4 in the local coordinate system with o3-o4 as the horizontal axis, as in the first embodiment of the first invention,
While sufficient torsional rigidity of the joint between the cross member 14 and the side rail nib 12W is ensured, the durability and strength of the joint can be improved and reliability can be improved. Here,
The area Ωi refers to the area represented by Ru2. Additionally, the upper vertical flange 14uf and the lower vertical flange 14tf in this embodiment may be provided so as to point away from each other as in FIG. may also be provided.

Further, FIGS. 9-11 show that cross member 14 has upper and lower flanges 14u and 14t and longitudinal web 14W.
The second embodiment is formed as a member having an I-shaped cross-sectional shape, and the other configuration is substantially the same as that of the first embodiment.
This shows a second embodiment of the invention. In this embodiment, the ends of the upper and lower flanges 14u and 14t of the cross member 14 in the vehicle width direction are each extended outward, and each extended portion is bent in the up and down direction to form the upper and lower flanges 14u and 14t.
uf and a lower vertical flange 14tf are formed. The above upper vertical flange 14uf and lower vertical flange 14tf
are respectively fastened cross-sectional groove type or port 20 u, 2
01, the web 12WKi of the side rail 12 is fastened.

Also for this embodiment, the upper and lower vertical flanges 14
uf and 14 tf and side rail 12 web 12W
20u and 20t (cross-sectional groove type or pole) 20u and 20t connected to each other, as in the first embodiment of the painter's invention and its modification, the bending lines o1-o2 of the upper and lower vertical flanges
．． By arranging it on the vertical flange surface other than the region Ω1 in the local orthogonal coordinate system with the horizontal axis o, -o4t, the connecting portion between the cross member 14 and the web 12w of the side rail can be fixed as in the first embodiment. While ensuring sufficient torsional rigidity, the stress sensitivity can be significantly reduced compared to conventional configurations, and the durability and reliability of the joint can be improved.

Among them, this example Vcf is -1+7. The arrangement of the l-furuno rdo lower sewing flanges 14uf and 14tf may be provided so as to point away from each other as in FIG. 5,
Further, as shown in FIG. 8, both may be provided facing downward, or conversely, both may be provided facing upward.

In each of the above embodiments and their variations, the surface on which the fastened cross-sectional groove type or melt is disposed is limited within the plane excluding the region where the above formulas representing each region 01 to Ω4 are both satisfied. Rather, a cross-sectional groove type or bolt fastened in the plane excluding the area satisfying at least one formula may be provided.

In addition, in all the embodiments of the first and second inventions described above and their modifications, the upper and lower vertical flanges 1
8uf, 14uf and 18tf, 1. The number of fastened cross-sectional grooves (poles) 20u, 20t that fasten the lf to the web 12W of the side rail can be increased or decreased as appropriate, and the front shape of each vertical flange is not limited to the rectangle shown, but may be trapezoidal or trapezoidal. You can also.

(Effects of the Invention) As described above, the truck chassis frame according to the first invention includes a pair of left and right side rails extending in the front-rear direction of the vehicle body and each having a groove-shaped cross section, and a pair of side rails extending in the width direction of the vehicle body. The extended portions of both ends of the left and right pair of upper and lower flanges were bent in the vertical direction to form vertical flanges, respectively, and the same vertical flanges were fastened to the web of the side rail by a plurality of fastened cross-sectional grooves or bolts. and an alligator-type cross member, in which a plurality of glue bents or belts that respectively fasten the upper vertical flange and the lower vertical flange to the web of the side rail satisfy the following formula for each vertical flange: Ωi (i=1~4; t=x and lower longitudinal flange, i=
3 and 4 are lower vertical flanges), that is, ξ: Coordinates in the direction along the bending line in the local coordinate system with the origin at both ends O of the bending line of the upper and lower vertical flanges, however, ξi: In the local coordinate system with O3 as the origin,
1. Coordinate a perpendicular to the folding line, 2. Length b of the bending line of the upper and lower vertical flanges = Distance between the bending lines of the upper and lower longitudinal flanges. The second invention is characterized in that it is not arranged in one area.
Vertical flanges are formed by vertically bending the extended portions of both ends of a pair of left and right side rails that extend in the longitudinal direction of the vehicle and each having a groove-shaped cross-sectional shape, and a pair of left and right upper and lower flanges that extend in the width direction of the vehicle. In the case where the same vertical flange is provided with a plurality of fastened groove-shaped cross members or a cross member having a groove-shaped cross section or type 1 shape fastened to the web of the side rail by means of a cross member, the above-mentioned upper vertical A plurality of fastened cross-sectional grooves or belts fastening the flanges and the lower longitudinal flange to the web of the side rail, respectively, have an area Ωi (i=1 to 4; i=1 and lower vertical flange, i = 3 and 4 are lower longitudinal flanges), i.e., ξ, 2. The coordinates in the direction along the bending line in the local coordinate system with the origin at both ends 01 of the bending line of the upper and lower longitudinal flanges, ξi: 2 Coordinate a perpendicular to the bending line in the local coordinate system with Oi as the origin, 2 Length of the bending line of the upper and lower vertical flanges b: Bending of the upper and lower vertical flanges It is characterized in that it is not disposed in at least one area defined by the formula of the distance between the lines, and in both inventions, the upper and lower side rails are formed at both ends of the side rail in the vehicle width direction. Arrangement of the fastened cross-sectional groove type or belt that fastens the vertical flange to the web of the night rail (' By adding a twist to the turn, the fastened cross-sectional groove shape while ensuring the torsion and bending rigidity of the fastening part) It has the advantage of effectively reducing the stress generated in the mold or gutter and the surrounding plate members, and improving IT durability and reliability, which is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a plan view of main parts showing a first embodiment of the first invention, and FIG.
The figure is a front view seen from the direction of the arrow ■ in FIG. FIG. 3 is a front view showing the arrangement/guts of the cross-sectional grooves or bolts fastened to the upper and lower vertical flanges shown in FIGS. 1 and 2, and FIG. 4 is a front view of the first embodiment described above. A diagram showing the stress sensitivity and torsional stiffness at the joint portion between the upper and lower vertical flanges and the side rail unibu in comparison with the conventional configuration, and FIG. 5 shows the second embodiment of the first invention. Front view similar to FIG. 2. FIG. 6 is a front view showing the cross-sectional groove type or belt arrangement pattern in which the upper and lower vertical seven runs are fastened in the second embodiment shown in FIG. 5, and FIG. FIG. 8 is a front view seen from the direction of the arrow ■ in FIG. 7; FIG. 9 is a plan view of essential parts showing the second embodiment of the second invention; FIG. 9 is a front view seen from the arrow X direction in FIG. 9, FIG. 11 is a side view seen from the arrow ■ direction in FIG. 9, and FIG. 12 is an upper and FIG. 4 is a front view showing a conventional fastened cross-sectional groove type or gutter device T4 turn on a lower longitudinal flange. 10... Chassis frame, 12... Side rail. 12W...Side rail nib, 14...Cross member 14uf and 18uf...Upper vertical flange, 1
4tf and 18tf...lower vertical flange, 20u and 20t...fastened cross-sectional groove type or bolt. Figure 1 Figure 2 Figure 3 Figure 4 Figure Fang 9 Figure 1 Construction drawing t 4w 201144f Oni 0 Figure 12

Claims (2)

[Claims] (1) A pair of left and right side rails extending in the front-rear direction of the vehicle, each having a groove-shaped cross section, and extending portions of both ends of the upper and lower flanges extending in the width direction of the vehicle are bent in the vertical direction. and an alligator-type cross member which is fastened to the web of the side rail by a plurality of rivets or bolts, wherein the upper vertical flange and the lower vertical flange are connected to the web of the side rail. The area Ω_i(i
= 1 to 4; i = 1 and 2 are upper vertical flanges, i = 3 and 4 are lower vertical flanges), that is, Ω_i: (ξ_i/a_i) + 3.8 (η_i/b)<
1 However, ξ_i: The coordinate in the direction along the bending line in the local coordinate system whose origin is O_i at both ends of the bending line of the upper and lower vertical flanges η_i: The coordinate in the direction along the bending line in the local coordinate system whose origin is O_i above. Coordinate in the right angle direction a_i: Length of the bending line of the upper and lower vertical flanges b: Distance between the bending lines of the upper and lower vertical flanges. A truck chassis frame that is not (2) A pair of left and right side rails extending in the front-rear direction of the vehicle, each having a groove-shaped cross-section, and extending portions of both ends of the upper and lower flanges extending in the width direction of the vehicle are bent in the vertical direction. The upper vertical flange and the lower vertical flange each have a groove-shaped or I-shaped cross member fastened to the web of the side rail by a plurality of rivets or bolts. A plurality of rivets or bolts that respectively fasten the vertical flanges to the web of the side rail satisfy the following formula for each vertical flange. and 4 is the lower vertical flange), that is, Ωi: (ξ_i/a_i)+5・(η_i/b)<1, where ξ_i: the bending point in the local coordinate system with O_i as the origin at both ends of the bending line of the upper and lower vertical flanges. Coordinate in the direction along the bending line η_i: Coordinate in the direction perpendicular to the bending line in the local coordinate system with O_i as the origin a_i: Length of the bending line of the upper and lower vertical flanges b: Length of the bending line of the upper and lower vertical flanges A truck chassis frame, characterized in that the frame is not disposed in at least one region defined by the formula for the distance between bending lines.